Well a while back in June I posted how I reluctantly switched over 70 Sylvania Incandescents to Sylvania Micro Mini CFL and was sad I made the decision but was reassured it was a smart move being I am pretty much nocturnal with me working 2nds and the wife working 3rds I have a tendency to turn a the lamps on in the home and do projects at night.  You guys were right on, not one problem with a single CFL and I was pleased to see my electric bill drop about $15 a month!  Now my garage is lit (was a wood shop) with 14 Utilitech magnetic ballast (but very cheap Chinese) T12 40watt double bulb fixtures and most have begun to flicker and new bulbs haven't helped.  If I swap bulbs around a few times oddly enough they stop for a few days but then it starts again...mostly when it's below 45 degrees or above 80 degrees.  So...my proposal is to swap all of them to electronic ballasted T8 fixtures like my father bought.  He bought a single 4 bulb Utilitech higher end for his work bench and I love how it comes right on!  Plus they would have pull chains so I could run half of them when not doing projects and save electricity.  My proposal is Lithonia two bulb electronic ballast fixtures, with T8 32 watt Sylvania 6500 K bulbs.  Overall should this be more reliable as well as in cold weather?  I have 3 buddies to whom have garages and I plan to donate the Magnetics to them as they said they would take.

Magnetic fixtures can go flickering due to bad connection somewhere in the line (and you better check for this first, esp. if the problem is with all the fixtures at once). You say you flip around the lamps and it helps, maybe what actually helps is that you disturb the bad connection when flipping the lamps

Other problem can be capacitors. There are ballasts with (HPF) and without (LPF/NPF) capacitors. The ones without have only the magnetic core, there is pretty much nothing that can fail in it. Capacitors however do fail and begin to misbehave. If the ballasts you have are with exposed capacitors, just try to replace the capacitor with new one of the same ratings and see if it fixed the issue. Otherwise (if the capacitor is potted inside), you may have to replace the ballast

If you have 240V available, you can use Euro type Switch Start (Preheat) and Perfect Start ballasts, both are very good and reliable, and as efficient as magnetic ballasts can get - which is pretty much efficient - the difference between them and electronics are few W which is not significant. besides, you can use them with the Euro 36W T8 energy saving lamps, and maybe T8 lamps available in the US as well, so save some more energy this way

Electronic ballasts have more reliability issues, and the power savings from them are less pronounced than changing incandescents to CFLs. After all, CFLs are 4 times more efficeint than incandescents, while electronic ballasts are only about 1.2 times more efficient than magnetic. I suggest to stay magnetic

@ Ash the only problem here in the US the European 36w preheat(Switch Start) tubes are hard to source in the US
they might be more common in the future as Vintage flourescent collector may have no choice to use 36 watt tubes
if triphospor T12 get too expensive. the 32 watt 4" work ok on modern single tube preheat ballast. but it get hard to start as lamp ages.

Electronic starters might help there. They are used on Preheat instead of ordinary starters

The electronic starter may start the F32T8, but they would be overloaded. And for some ballasts the F32T8 130V arc voltage could be too high to sustain the arc.

I don't think the tri-phosphor F40T12 would be ever so expensive to justify an individual import of 4' long fragile lamps from overseas, the postage use to be really high.

Of course, if they won't be available at all, it would become another story...

Well guys I did it, I replaced the 14 magnetic ballast 48 inch double bulb shop lights with 14 Lithonia electronic ballast T8 All Season fixtures, Sylvania 6500 Kelvin bulbs. I donated four of the magnetics to my dad for a shed, the rest to two friends to light their garages with. The new lower wattage bulbs are actually quite a bit brighter, but seem about the same if memory serves me correct what the T12's work two years ago when I bought the house and set them up.. let me tell you though I really miss flipping the switch and hearing 14 on the magnetic ballasts very loud when they were cold. Instead now I just get blinded with a burst of light and no sound silence is actually quite lonely LOL. I just got too frustrated with swapping bulbs around having one fixture after another act up. I realize that is probably because I had the cheapest of the cheapest chineese choke ballasts and not real american made magnetic ballast setup, I could have taken the advice converted to that as you guys suggested but I did not unfortunately. So it is kind of a bittersweet ordeal here, I am very satisfied with instant light but I miss the organicness of the magnetics. It is net to finally try Lithonia though, that brand always interested me, do they make decent other stuff? Oh, one important thing I forgot to mention to also Lithonia fixtures were dead on arrival! So I have to make a trip back and get two others which work fine!

Are you on 120V ? If yes, the ballasts for F40 cannot be chokes but they have to be some kind of autotransformer ballasts

Those can degrade but for what i know it will allways be the capacitor and not the ballast itself. From what i seen, Chinese ballasts are quite simply constructed so it should not be an issue to replace the capacitors

Hey Ash, yeah i have 120v here!  I always wondered this, can a regular fluorescent sustain arc at 120 volts if it is ignited with a few  kV like an inductance kick, or does the arc need more juice hence auto transformer?  This is interesting! I did open one old fixture up but didn't see a separate cap, would I have had to open the black ballast case to find the capacitor? Thanks man!

Hey Ash, yeah i have 120v here!  I always wondered this, can a regular fluorescent sustain arc at 120 volts if it is ignited with a few  kV like an inductance kick, or does the arc need more juice hence auto transformer?  This is interesting! I did open one old fixture up but didn't see a separate cap, would I have had to open the black ballast case to find the capacitor? Thanks man!

The discharges usually need moreless constant current source to let the arc control the voltage. The current source have to have enough voltage room, so the current is not influenced by the eventual arc voltage fluctuations, otherwise the arc become unstable.
But with AC supply, the current have to sometimes change the polarity. That mean in one moment it drop to zero, so the arc extinguish. But to remain lit continuously (as perceived by the users), it have to immediately restrike for the opposite polarity. For this reignition, the ballast should provide an OCV about twice the arc voltage just in the moment, when the current disappear, or as soon as possible. This is the reason, why the inductance is so important in the ballast impedance - the inductance change current only, when there is a voltage across it. So during the zero cross, the rest of the circuit should be at an instant with higher voltage (to allow the inductor current to change, so drop to zero), while the same voltage is then available for the lamp reignition just after the zero cross. As the ionization in the lamp does stay some while after the current disappear (but it is decaying), such reignition by far does not require so high voltage as when the lamp is turned ON, usually ~20..30% above the arc voltage reignite it. But for the reliability, the available voltage have to be twice the arcV, as if it does not reignite, it mean the lamp goes out and need to be normally restarted (one misfire in 1 million already mean the lamp extinguish after few hours)

At the same time the current should not vary as much with mains and/or arc voltage fluctuations. So when assuming the ballast is a linear impedance and the OCV is twice the lamp arc voltage, the current change about 7% with 5% mains voltage change, what is quite a lot. If usual core nonlinearity is added, the change is usually about 10% for 5% voltage change, what is just marginal to be accepted.

At the same time the ballast should provide clear differerence in some parameter for the ignition device to distinguish running from not existent arc.
Normal glowbottle starters and HPS electronic ignitors use the voltage across the lamp (higher than some threshold mean arc is OFF, so the starter kick in, lower voltage mean the lamp is running, so starter stand by). But that require the ballast to provide enough OCV, to allow the starter threshold to be set with sufficient margin above the lamp arc voltage (to not interfere with running lamp), yet the OCV to be way above the starter trhreshold (to kick in after power ON). This ask for at least twice the arc voltage as well.

Now this could be accomplished by few ways:
The easiest is to use the lamp of maximum half of the mains voltage and simple series inductor
Use an autotransformer with output about twice the lamp arc voltage and a series inductance.


Or one option remain for situations, where the mains is at least 20% higher than the arc voltage: Use series LC, operating near the resonance at low current, but the coil softly saturating at the desired operating current. The inductor saturation then move the resionance further above the mains frequency, increasing the impedance, so lowering the current. This mechanism then regulate pretty constant current even when the voltage headroom of the mains above the arc voltage is quite small.
The components should be designed so, the voltage across the capacitor on the normal current is about the mains voltage.
In this configuration during the current zero cross the capacitor's voltage add up to the rather low mains, where this sum is the voltage available for the past zero cross reignition.
But as the capacitor provide it's voltage only after there were any current, it is not present at power ON. So this circuit does not provide sufficient voltage for the starter to recognize the present/missing arc by the voltage, so it require the circuit current to be used as the control "signal" for the starter. So it need a thermal starter, glowbottles won't work here.

What model of Lithonia lights did you get, and how do you like them.

They are actually just called Lithonia All Season Shop Lights! :-). I love them they come on instantly with no noise at all like an incandescent, although I miss the magnetic hum a lot :-/ the bulbs still take a minute to reach full brightness as the mercury vaporizes akin to a CFL.  If you google Lithonia All Season Shoplight you will see them! They are grey!

And thank you thank you for that detailed explanation of voltage and current across a fluorescent lamp!!

Lithonia used to make good quality lighting products in Lithonia, Georgia, USA.  In recent years, they seem more like a "discount" maker, with most of their products being made in China. I have some very nice commercial grade Lithonia 4 tube HO 4 foot fixtures.  I have also replaced a lot of their later made junk.  Bottom line: if you are happy with your purchase, that is what really matters.  If you want some magnetic hum, you can always hang a good ole magnetic ballasted fixture over a work bench or table.

The older Lithonia products were pretty good, I have a couple of older HO 4' striplights (UN 2 48HO 120 CW20) from Lithonia and they were pretty pretty well made and included a Advance ballast. One of mine is missing a ballast cover though.

I've also noticed their product's quality slipped a bit recently, now the striplights have thinner metal and tend to come with cheapo Accupro electronic instant start ballasts.   

Hey guys, an update!  It's been a few weeks!  All 14 Lithonias are still working perfectly, they start instantly and are silent, and come to full brightness within about a minute or two.  I am excited to see how they perform in the fall and winter here as it gets very cold!  Yes I observed the lower build quality you speak of!  Two fixtures did not work, they were dead right out of the box, and a third was missing the rubber grommet around where the power cord enters the fixture.  I returned those three to the store for another random three off the shelf and they worked fine!  The ballasts in them are Keystone ballast from right here in Pennsylvania! I opened up one of the defective ones.  Lithonia is itself a company from Georgia as you said, states the box.  But they were assembled in Mexico...by pretty lax workers I'd say LoL!!